In his new book, "Let it Shine: The 6,000-Year Story of Solar Energy," author John Perlin describes fascinating new discoveries, how people of today can learn from the solar engineers of ancient times and examines the prospects of solar for future generations.
pv magazine: How would you describe the book?
John Perlin: What the book does is differentiate all of the solar technologies. Through telling stories of the different technologies and how they work, people understand what you can do with the various aspects of solar energy. All these are told in story form using people. Because our brains are built for listening to stories rather than going through technical manuals, all this information adheres better in this form. This book is the story of how our industry laid down solid roots in solar 6,000 years ago, up to the last buds that are beginning to flower today. It encompasses all the solar technologies in that fashion.
You published a version of this book back in 1980: "A Golden Thread: 2500 Years of Solar Architecture and Technology." How did the new version come about?
I was making amazing discoveries and it was sort of like the multicolored coat of Joseph, or a quilt, compiling all these new discoveries. I realized I wanted to do a new version because there is so much more to the history of solar energy than we published in 1980. The book is twice as long as the old one, so its basically a new book.
What were some of new surprising discoveries you made while researching the book?
I made a lot of discoveries. For example, the famous Roman architect Vitruvius was a very big promoter of solar in his day. I discovered the reason was because during his military service he spent his time as a military engineer in Greece, where he saw these amazing solar cities. All the connections became clear as I was researching and reading, but there were also a lot of serendipitous incidents. For example, a Chinese group of [post-doctorate researchers] came to the University of California, Santa Barbara where I research. I met their wives, who also had PhDs and impeccable command of English. [Discussing the history of solar energy in China], they said they had access to documents more than 3,000 years old, and offered to translate them.
Another example: I was helping a Chinese scholar with the history of solar energy and he said there was one thing he could help me with. Just recently they had dug up multiple solar concentrators that dated back 3,000 years. There was written evidence, which appeared in the old book, but never before had they had the actual device on hand. But once again, all the archaeological papers on the subject are in Chinese and had never been translated, so I got them translated. It turned out they discovered a factory that had 30,000 molds for what they call yang-sui, or solar igniters, which Confucius wrote about. It was the duty of the eldest son to put on a yang-sui every morning to get the dinner fire going when the sun was out. They were made of highly polished bronze. What the Chinese archeologist found was a wok-like device but with handles on the back, so he polished it to its original luster and then focused it on some kindling and about 10 seconds later he had a fire. These were like matches or lighters of today.
It’s a fascinating connection: the Chinese, who are the major manufacturers of PV today, were, thousands of years ago, the major manufacturers of concentrators and, even earlier, the major designers of whole solar cities. In fact, the first solar city, which I discuss in the book, was laid out 4,000 years ago, and yet Beijing, which was a much newer city, also had the same layout.
Read the rest of the interview in the current issue of pv magazine.
John Perlin works at the University of California, Santa Barbara, Department of Physics and Student Affairs, where he mentors those involved in realizing photovoltaic, solar hot-water and energy-efficiency technologies.